In rats, cortical spreading hyperaemia is coupled to a spreading neuroglial depolarization wave (spreading depression) under physiological conditions, whereas cortical spreading ischaemia is coupled ...to it if red blood cell products are present in the subarachnoid space. Spreading ischaemia has been proposed as the pathophysiological correlate of the widespread cortical infarcts abundantly found in autopsy studies of patients with subarachnoid haemorrhage. The purpose of the present study was to investigate whether the extracellular ion changes associated with the depolarization wave may cause the vasoconstriction underlying spreading ischaemia. We induced spreading ischaemia in vivo with the nitric oxide (NO) scavenger oxyhaemoglobin and an elevated K+ concentration in the subarachnoid space while slow potential, pH, extracellular volume and concentrations of K+, Na+, Ca2+ and Cl− were measured in the cortex with microelectrodes. We then extraluminally applied an ionic cocktail (cocktailSI) to the isolated middle cerebral artery in vitro, matching the ionic composition of the extracellular space as measured during spreading ischaemia in vivo. Extraluminal application of cocktailSI caused middle cerebral artery dilatation in the absence and constriction in the presence of NO synthase inhibition in vitro, corresponding with the occurrence of spreading hyperaemia in the presence and spreading ischaemia in the absence of NO in vivo. The L-type Ca2+ inhibitor nimodipine caused the cocktailSI-induced vasoconstriction to revert to vasodilatation in the absence of NO in vitro similar to the reversal of spreading ischaemia to spreading hyperaemia in response to nimodipine in vivo. We found that K+ was the predominant vasoconstrictor contained in cocktailSI. Its vasoconstrictor action was augmented by NO synthase inhibition. Our results suggest that, under elevated baseline K+ as a hallmark of any condition of energy deficiency, the extracellular ion changes represent the essential mediator of the vascular response to spreading neuroglial depolarization. In the presence of NO they mediate vasodilatation and in its absence they mediate constriction.
The n-octanol-water partition coefficient (logP) is an important physicochemical parameter which describes the behavior of organic compounds. In this work, the apparent n-octanol/water partition ...coefficients (logD) of basic compounds were determined using ion-suppression reversed-phase liquid chromatography (IS-RPLC) on a silica-based C18 column. The quantitative structure-retention relationship (QSRR) models between logD and logksub.w (logarithm of retention factor corresponding to 100% aqueous fraction of mobile phase) were established at pH 7.0-10.0. It was found that logD had a poor linear correlation with logksub.w at pH 7.0 and pH 8.0 when strongly ionized compounds were included in the model compounds. However, the linearity of the QSRR model was significantly improved, especially at pH 7.0, when molecular structure parameters such as electrostatic charge nsub.e and hydrogen bonding parameters A and B were introduced. External validation experiments further confirmed that the multi-parameter models could accurately predict the logD value of basic compounds not only under strong alkaline conditions, but also under weak alkaline and even neutral conditions. The logD values of basic sample compounds were predicted based on the multi-parameter QSRR models. Compared with previous work, the findings of this study extended the pH range for the determination of the logD values of basic compounds, providing an optional mild pH for IS-RPLC experiments.
Osmotically driven membrane processes, such as forward osmosis (FO) and pressure-retarded osmosis (PRO), rely on the utilization of large osmotic pressure differentials across semi-permeable ...membranes to generate water flux. Previous investigations on these two processes have demonstrated how asymmetric membrane structural characteristics, primarily of the support layers, impact water flux performance. In this investigation we demonstrate that support layer hydrophilicity or wetting plays a crucial role in water flux across asymmetric semi-permeable membranes. The results show that the polyester (PET) non-woven and polysulfone supports typically present in thin-film composite (TFC) reverse osmosis (RO) membranes do not wet fully when exposed to water, thereby resulting in a marked decrease in water flux. A cellulosic RO membrane exhibited modestly higher water fluxes due to its more hydrophilic support layer. Removal of the PET layers from the cellulosic and TFC RO membranes resulted in an increased water flux for the cellulosic membrane and very little change in flux for the TFC membrane. Pretreatment with hydraulic pressure (RO mode), feed solution degassing, and use of surfactants were used to further elucidate the wetting mechanisms of the different support layers within each membrane. The importance of considering membrane support layer chemistry in further development of membranes tailored specifically for osmotically driven membrane processes is discussed.
The major sources of fine particulate matter (PM2.5) in New York City (NYC) were apportioned by applying positive matrix factorization (PMF) to two different sets of particle characteristics: mass ...concentrations using chemical speciation data and particle number concentrations (PNC) using number size distribution, continuously monitored gases, and PM2.5 data. Post-processing was applied to the PMF results to: (i) match with meteorological data, (ii) use wind data to detect the likely locations of the local sources, and (iii) use concentration weighted trajectory models to assess the strength of potential regional/transboundary sources. Nine sources of PM2.5 mass were apportioned and identified as: secondary ammonium sulfate, secondary ammonium nitrate, road traffic exhaust, crustal dust, fresh sea-salt, aged sea-salt, biomass burning, residual oil/domestic heating and zinc. The sources of PNC were investigated using hourly average number concentrations in six size bins, gaseous air pollutants, mass concentrations of PM2.5, particulate sulfate, OC, and EC. These data were divided into 3 periods indicative of different seasonal conditions. Five sources were resolved for each period: secondary particles, road traffic, NYC background pollution (traffic and oil heating largely in Manhattan), nucleation and O3-rich aerosol. Although traffic does not account for large amounts of PM2.5 mass, it was the main source of particles advected from heavily trafficked zones. The use of residual oil had limited impacts on PM2.5 mass but dominates PNC in cold periods.
•Major sources of PM2.5 mass and particle number concentrations are apportioned in NYC.•Nine sources resolved over PM mass; 5 for particle number concentration.•Temporal patterns, weather, wind data and regional transport used for interpretation.•Relationships between results on PM mass and number concentrations investigated.•Air quality status and atmospheric processes over the NYC area are discussed.
Heavy metal (HM) pollution in agricultural soils has arisen sharply in recent years. However, the impact of main factors on available HMs concentrations in agricultural soils of the three main ...industries (smelting, chemical and mining industry) is unclear. Herein, soil properties (pH, cation exchange capacity (CEC) and texture (sand, slit, clay)), total and available concentrations were concluded based on the results of 165 research papers from 2000 to 2023 in Web of Science database. In the three industries, the correlation and redundancy analysis were used to study the correlation between main factors and available concentrations, and quantitatively analyzed the contribution of each factor to available concentrations with gradient boosting decision tree model. The results showed that different factors had varying degrees of impact on available metals in the three main industries, and the importance of same factors varied in each industry, as for soil pH, it was most important for available Pb and Zn in the chemical industry, but the total concentrations were most important in the smelting and mining industry. There was no significant correlation between total and available concentrations. Soil properties involved in this paper (especially soil pH) were negatively correlated with available concentrations. This study provides effective guidance for the formulation of soil pollution control and risk assessment standards based on industry classification in the three major industrial impact areas.
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•Soil properties and total concentrations were main factors for available HMs.•There was no significant correlation between total and available concentrations.•Slit and pH had a significant contribution degree in chemical and mining industry.•The importance ranking of main factors was total concentrations﹥pH﹥texture﹥CEC (except for Cu) in the three industries.
Of the hundreds of thousands of Ukrainian women were sentenced to
the Gulag in the 1940s and 1950s, only half survived. In
Survival as Victory , Oksana Kis has produced the first
anthropological ...study of daily life in the Soviet forced labor
camps as experienced by Ukrainian women prisoners. Based on the
written memoirs, autobiographies, and oral histories of over 150
survivors, this book fills a lacuna in the scholarship regarding
Ukrainian experience. Kis details the women's resistance to the
brutality of camp conditions not only through the preservation of
customs and traditions from everyday home life, but also through
the frequent elision of regional and confessional differences.
Following the groundbreaking work of Anne Applebaum's Gulag: A
History (2003), this book is a must-read for anyone interested
in gendered strategies of survival, accommodation, and resistance
to the dehumanizing effects of the Gulag.
pH and salt effect on the removal of methyl orange dye. Display omitted
► The prepared CMK-3 is a good replica of its template SBA-15. ► Adsorption process was fast enough, and 60min contact time is ...sufficient. ► CMK-3 is an excellent adsorbent for dye removal. ► It is a good replacement of commercially available carbons.
The mesoporous carbon CMK-3 adsorbent was prepared, characterized, and used for the removal of anionic methyl orange dye from aqueous solution. Adsorption experiments were carried out as batch studies at different contact time, pH, initial dye concentration, and salt concentration. The dye adsorption equilibrium was rapidly attained after 60min of contact time. Removal of dye in acidic solutions was better than in basic solutions. The adsorption of dye increased with increasing initial dye concentration and salt concentration. The equilibrium data were analyzed by the Langmuir and Freundlich models, which revealed that Langmuir model was more suitable to describe the methyl orange adsorption than Freundlich model. Experimental data were analyzed using pseudo-first-order and pseudo-second-order kinetic models. It was found that kinetics followed a pseudo-second-order equation. Thermodynamic study showed that the adsorption was a spontaneous and exothermic process.
In article number 2006768, Hyukjin J. Kwon, Geunbae Lim, and Minsoo Lee introduce a multiscale‐porous anion exchange membrane (MP‐AEM), as an easily accessible anion‐permselective material for the ...electrokinetic concentration of cationic species. The MP‐AEM's highly streamlined fabrication process enables convenient cation‐selective electrokinetic concentrator assembly, and its demonstrated scalability shows great potential for use in a variety of high‐throughput applications.
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